Poisonous Pigments: History’s Deadliest Colors
Throughout history, ancient civilizations have been using all kinds of ingenious ways to create pigments for the coloring of clothing, objects and even buildings. While some of the pigments were truly magnificent and striking, many were also deadly.
Prior to the early modern period, most pigments were obtained from natural sources, either of organic or inorganic origin. With the advent of the scientific and industrial revolutions, the range of synthetic pigments was greatly increased.
Bright but Deadly: Lead White
One of the most commonly used pigments that has posed a threat to human health is lead white (also known as white lead), which can be traced back at least 2,500 years, making it among the earliest synthetic pigments produced by human beings.
This color is mentioned by the 4th / 3rd century BC philosopher Theophrastus of Eresos, who states in his work, On Stones, that lead white may be obtained by mixing metallic lead with vinegar.
This particular recipe is repeated by other Classical authors, including Pliny, who gave the following description in his work Natural History:
“It is made from very fine shavings of lead, placed over a vessel filled with the strongest vinegar; by which means the shavings become dissolved. That which falls into the vinegar is first dried, and then pounded and sifted, after which it is again mixed with vinegar, and is then divided into tablets and dried in the sun, during summer.”
Around the same time, i.e. the 4th century BC, a similar procedure was being used by the Chinese to produce lead white.
While lead white was a favorite among European painters, more tragically, it was used by ancient Egyptians, Greeks and Romans in the preparation of ointments and cosmetics, with dire consequences.
The chemical element of lead white, with the formula 2PbCO3.Pb(OH)2, is extremely harmful to humans and animals and can be introduced into the body via one of three ways – inhalation, skin absorption, and ingestion.
Symptoms of lead poisoning (referred to also as ‘painters’ colic’ or ‘plumbism’) vary depending on age groups. An adult exposed to lead, for instance, may experience headaches, abdominal pains, joint and muscle pain, and high blood pressure, whereas children may suffer from developmental delays, learning difficulties, and weight loss.
Venetian ceruse was a 16th-century cosmetic used as a skin whitener. It used white lead as a pigment causing lead poisoning, damaging the skin and causing hair loss. (Jdforrester / Public Domain)
Lead white was used by European painters well beyond the Classical period. The importance of this pigment is evident in the fact that up until the 19th century, lead white was the only white pigment used in European easel painting. It was only during the 20th century that an alternate white pigment, titanium dioxide whites, became available to painters.
Compared to lead white, this new pigment is non-toxic. Nevertheless, lead white has certain advantages over its titanium counterpart.
For instance, lead white is a warmer and softer white than titanium white, which means that it is more suitable for painting flesh tones. Thus, lead white is still in use even today. Be that as it may, by taking the necessary precautions, an artist can avoid poisoning himself / herself while using this pigment.
The Dread of Red Lead
Lead white is not the only pigment containing lead. Another pigment with this chemical element is red lead, which has the chemical formula Pb3O4. This pigment is also known as minium, which is derived from the Minius River in northwest Spain.
It was from there that the naturally occurring mineral minium was mined in antiquity. The use of natural lead red ceased once a synthetic form of the pigment was discovered.
Vitruvius reports that red lead was discovered by chance when lead white was cast into a fire, and notes that the synthetic product was much better than the natural one. Synthetic lead red was also being produced in China as early as the Han dynasty, and there is no evidence that the natural form of this pigment was ever used there.
The earliest example of red lead being used directly (as opposed to being mentioned in a literary source) comes from Egypt. This pigment is found to have been applied on the Fayum mummy portraits, which date to between the 2nd and 4th centuries AD. The use of red lead has also been identified further east, for instance, on wall paintings in central China (dating to between the 5th and 9th centuries AD), and Buddhist wall paintings from Afghanistan (6th century AD).
Red lead was also used extensively in medieval manuscripts, and the word ‘miniature’ is connected to ‘minium’ through the Latirn verb ‘miniare’, which means ‘to write with minium’. In ancient times, red lead was often used to adulterate cinnabar, another deadly pigment that will be discussed later on.
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The Códice del Escorial (1272-1284) from Spain. Medieval manuscripts often used red-orange minium pigment in the letters of the text and for small illustrations, called miniatures. (Escarlati / Public Domain)
Never Use Naples Yellow
Yet another dangerous pigment where lead is present is lead antimonate yellow, known also as Naples yellow. The pigment has the following chemical formula, Pb3(SbO4)2 and it is a salt of two highly toxic metals, lead and antimony, and is therefore extremely poisonous.
Naples Yellow was initially used in ancient Egypt and Mesopotamia as a yellow colorant and opacifier in glasses and glazes.
Unlike some other pigments, lead antimonite yellow was lost and re-discovered several times throughout history, reaching its height of popularity in European art between 1750 and 1850 and, during this time, it was the dominant yellow pigment used by landscape artists. After this period, lead antimonate yellow was slowly replaced first by chrome yellow and then by cadmium yellow.
Roman glass beaker from second half of the 4th century. The yellow pigment is derived from lead antimonate. (MatthiasKabel / CC BY-SA 4.0)
Toxic Mercury in Vermilion
Lead is not the only chemical element that is dangerous to human beings. Mercury is another element known today for its lethality, and is found in cinnabar, a mineral used in ancient times for the production of a bright red / scarlet pigment known as vermilion.
Mercury exists in three forms – elemental, organic, and inorganic. The mercury found in cinnabar is inorganic, and the least dangerous form of the three. Nevertheless, it is still poisonous and may enter the body in ways similar to lead, i.e. inhalation, skin absorption, and ingestion.
Symptoms of mercury poisoning in adults include muscle weakness, lack of co-ordination, and difficulties in speech and hearing. On the other hand, children and infants exposed to high levels of mercury may suffer from retardations in speech and language development, cognition, and visual-spatial awareness.
In spite of its toxicity, cinnabar has been used, either on its own as a mineral, for the production of vermilion since ancient times. As an example, ground cinnabar is said to have been used in early Chinese burials.
During the Shang and Zhou Dynasties, i.e. 2nd and 1st millennia BC, ground cinnabar was scattered in graves, due to the belief that it was capable of preserving the bodies of the dead. Cinnabar was also an important mineral in ancient Chinese alchemy and was one of the ingredients required for the making of the legendary philosopher’s stone.
The red pigment cinnabar was used in this Chinese carved lacquerware, from the late Qing dynasty. (Danieliness / CC BY-SA 4.0)
Cinnabar was also known to the ancient Romans. Vitruvius, for instance, wrote about the process of producing vermilion from cinnabar. According to the ancient author, the extracted mineral is first dried and crushed. After this it is washed and heated repeatedly so as to remove impurities and to bring out the color.
Once the pigment is ready, it may be used for coloring the polished stucco of interior walls, as the pigment is stable so long as it is not exposed to sunlight. Exposure to sunlight causes a chemical reaction in the pigment which results in color loss. Hence, there are cases where vermilion changes from its original bright red color to brown, black, or grey over time.
Synthetic vermilion appeared during the 8th century AD, and it is thought that the process was discovered by the Chinese. It is likely that this knowledge was brought to the West by the Arabs. In the centuries following its discovery, synthetic vermilion was widely used as a pigment by Western artists.
Some Western works of art in which vermilion was used include Titian’s Madonna and Child (1570s), Ruben’s Descent from the Cross (17th century) in Antwerp Cathedral, and Raphael’s The Crucifixion (1503). Vermilion was not used uniquely by Western artists and the use of this pigment may be found on Asian works of art as well. These include Mughal Indian wall paintings from the 17th century, as well as various Chinese and Japanese paintings on paper and silk (dated to between the 13th and 19th centuries).
Green Arsenic Killer Pigments
Unlike the other pigments mentioned so far, the next deadly pigment did not exist in the ancient world and was only invented during the 18th century. Scheele’s Green was named after its inventor, Carl Wilhelm Scheele, a Swedish chemist who was conducting research on arsenic at the time.
Scheele first produced this synthetic green pigment in 1775 by adding arsenious oxide (As2O3) to heated sodium carbonate (Na2CO3). The mixture would then be stirred, until completely dissolved, thus producing a sodium arsenite (NaAsO2) solution. Finally, copper sulfate [CuSO4(H2O)x] would be added, so as to provide the bright green color this pigment is known for. Thus, Scheele’s Green has a chemical formula of AsCuHO3.
Prior to the invention of Scheele’s Green, green was derived from copper carbonate pigments, including verdigris and malachite. Compared to Scheele’s Green, however, these green pigments are duller and less durable. In addition, Scheele’s green pigment mimicked the green color of foliage better than its older counterparts.
Lastly, Scheele’s Green was cheap and easy to make. Therefore, Scheele’s Green replaced older green pigments soon after its discovery. This new green pigment was not only used for paintings, but also for a variety of everyday products, including wallpaper, fabrics, and even some children’s toys.
Damage caused by the use of green arsenic, 1859, from Scheele’s Green pigment. (Fæ / CC BY-SA 4.0)
The popularity of Scheele’s Green, however, did not last for long. This was not due to the fact that it was poisonous, but due to the invention of another green pigment, emerald green, known also as Paris green. This pigment was invented in 1808 and was meant to be an improvement of Scheele’s Green.
Indeed, it quickly displaced Scheele’s Green when it became available commercially in 1814. Like Scheele’s Green, emerald green was laden with arsenic, and therefore, was not really an improvement from its predecessor, from a health and safety point of view.
It is unclear as to when exactly Scheele’s Green ceased to be used, while emerald green continued to be used as a pigment right up until the 1960s in Europe and the United States. Although it was no longer used as a pigment, emerald green functioned as an insecticide until the early 1980s.
The fact that both Scheele’s Green and emerald green were used in everyday products meant that more people were at risk of being poisoned, as compared to those pigments whose use was limited to painters. This was not limited to those who used these arsenic laced products, but also those involved in producing them.
The death of Matilda Scheurer, a 19th century London flower maker, was widely publicized, and highlighted the dangers of arsenic in these green pigments. At that time, artificial flowers were in vogue, and artificial leaves were dusted with green powder to make them look more natural and realistic.
Workers in such factories were therefore exposed to arsenic, which entered their bodies through inhalation. The autopsy of Scheurer showed that the arsenic she had inhaled had reached her internal organs, i.e. her stomach, liver, and lungs, and had destroyed her from the inside out.
Another possible victim of Scheele’s Green / emerald green was Napoleon Bonaparte. After his defeat at the Battle of Waterloo in 1815, the French emperor was exiled to Saint Helena, an island in the South Atlantic Ocean, where he stayed in a room painted green.
It has been speculated by some that it was the arsenic from the wallpaper that caused his death. Although analysis of Napoleon’s hair revealed significant amounts of arsenic, modern analyses of the wallpaper found that the arsenic content in them was enough to cause illness, but probably not death.
The death of Napoleon is speculated to have been caused by arsenic from the green pigment in the wallpaper and paint in his room. (Fæ / Public Domain)
Uranium Orange: The Radioactive Pigment
The last deadly pigment of this article is uranium orange, which is a product of the 20th century. Unlike the rest of the pigments in this article, uranium orange was not used by painters, but specifically as a ceramic glaze.
In 1936, a line of glazed ceramic dinnerware known as Fiesta (or Fiestaware) was introduced in the United States. The original Fiesta came in five colors – red, blue, green, ivory, and yellow, with red being the most popular color. In order to obtain this red, uranium oxide was added into the glaze.
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Fiestaware was first made in 1936. To achieve the bright colors uranium oxide was added into the glaze. (Marc Soller / CC BY-SA 2.0)
From the start of its production till 1943, natural uranium was used. During World War II, the company’s supply of uranium was confiscated by the government, as it was needed for the production of nuclear weapons. When production resumed in 1959, depleted uranium was used instead.
Needless to say, uranium is a radioactive element and eating off a plate with a uranium-based glaze increases the risk of developing tumors or cancer, especially in the gastrointestinal tract. Modern Fiesta dishes, fortunately, are not radioactive, as depleted uranium was used in the ceramic glazes only until 1972/3.
While science continues to discover that many of the chemicals we use today in cosmetics, household products and even food are harmful, for now it appears we have eliminated the danger of deadly pigments.
Top image: Several of the ancient pigments were deadly. Photo source: Ezume Images / Adobe Stock.
By Wu Mingren
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